1. Field of the Invention.
The present invention relates to power tools driven by pneumatic force means. More particularly, the invention relates to air driven power tools for applying high torque forces to turn objects.
2. Description of the Prior Art.
For many years tradesmen and workmen of many skill and trade classifications have used pneumatic power tools, i.e., tools driven by air. Thus, gun type reversible impact air wrenches of many types and designs have been used, particularly by auto service personnel, for loosening and removing, and for applying and tightening, the machine nuts applied to the lug bolts by which automobile wheels are mounted. Further, reversible air driven ratchets have been used by auto and other mechanics to set and remove machine nuts and bolts and other hand held pneumatic tools have been designed and manufactured as rotary drills, reamers and tapping machines and for driving screw driver blades and other mechanical tools and implements. All of such tools and devices have quick connect means for attachment of the tool or device to a flexible air hose of the type commonly available in auto repair and service garages, machine shops, oil refineries, chemical and power plants and other facilities wherein machinery, piping and devices of all types are in service, use and/or under repair.
In oil refineries, chemical plants, power plants and other industrial facilities (also outside or exposed pipe lines) there are multiple systems of heavy pipe lines with associated valves. Such valves, including large gate valves, globe valves, angle valves and cross valves, are most commonly operated by handwheels which may have a diameter of as much as 24 inches and greater. The handwheels (usually of rim and spoke design) drive inside or outside screw stems which lift (open) or drop (close) or otherwise move the valve disk with respect to the valve seat. For large gate valves, used in pipe lines of twelve or more inches in internal diameter, it may require fifty or more turns of the valve handwheel to fully open or close the valve. Frequently, where large gate, globe and angle valves are not regularly opened and closed or are exposed to corrosive atmospheres, hand operated valves stick or "freeze" in one position or another and the opening or closing thereof requires the application of heavy to extreme torque force to the handwheel to free or "break" the locking forces (corrosion, etc.) tending to hold the valve components in place. Even where such valves are operated regularly, heavy torque forces may be required to be applied to the valve' s handwheel by a plant operator or mechanic to open or close the valve over a great number of handwheel turns.
It is an object of the present invention to provide a pneumatic torque wrench adapted for use in the force rotation of handwheels associated with large gate valves, globe valves, angle valves and cross valves.
It is another object of the invention to provide an air driven torque wrench which is adaptable to the spoked handwheels of a wide variety of large pipe line valves and which apply sufficient torque force to the handwheels to "break" the sticking forces commonly associated with such valves and thereafter rotate the handwheels to the extent of desired open or closed valve positions.
Other objects and advantages of the invention will be apparent from the following summary and detailed description of the invention, taken together with the accompanying drawing figures.